Slide projector transfer mechanism with stop means



J. A. CLARK SLIDE PROJECTOR TRANSFER MECHANISM WITH STOP MEANS 2Sheets-Sheet 1 Original Filed Feb. 16, 1959 BY .1 f $45 ATTORNEYS y 1965J. A. CLARK 3,195,252

SLIDE PROJECTOR TRANSFER MECHANISM WITH STOP MEANS 2 Sheets-Sheet 2Original Filed Feb. 16, 1959 INVENTOR.

JAM ES A CLA'R K ATTORNEY S United States Patent 3,195,252 SLEBEPROJECTQR TRANSFER MECHANISM WITH STOP MEANS James A. Clark, Brighton,N.Y., assignor to Banach & Lomh Incorporated, Rochester, N.Y., acorporation of New York Original application Feb. 16, 1959, Ser. No.793,569, now Patent No. 3,114,806, dated Dec. 17, 1963. Divided and thisapplication May 10, 1961, Ser. No. 199,144

2 Claims. (Cl. 40-36) This is a division of my copending applicationSerial No. 793,569, filed February 16, 1959, now Patent No. 3,114,806issued December 17, 1963.

The present invention relates to projection apparatus and, moreparticularly, to a slide projector projecting transparencies such asslides.

In instruments of this general character, there is usually employed anumber of integrated mechanisms which cooperate to perform the desiredresult of semi-automatic or automatic projection. To this end, there isusually provided a slide pickup and return mechanism, an automatic timercontrol, a slide tray indexing or feeding device, and a circuit havingvarious switches which are actuated in predetermined sequences tomaintain automatic action. The present invention contemplates animproved combination of a motor, slip drive connection, and interferencestop, and means to improve the stop by a stray magnetic field.Therefore, it is the principal object of the present invention toprovide an improved automatic slide projector embodying various improvedfeatures inherent therein.

FIG. 1 is a plan view of a projector;

FIG. 2 is a partial sectional view taken along the line 4-4 in FIG. 1.

Referring to the drawings and more particularly to FIGS. 1 and 2, thereis shown a slide projector having a base 16 for mounting a suitabledecorative cover cabinet (not shown) and for mounting the variousmechanisms of the present invention. Arranged on the base 16 is a lightsource 12, a projection system 14, a slide tray holder 16, slide pickupand a control panel 21) for supporting various electrical controldevices.

The light source 12 is shown as including a housing or shield 22 whichis suitably mounted on the base '10 and serves to protect a conventionalprojector lamp 24. The housing has a top plate 26, and a slidereceptacle 36 for holding a slide S when the same is in projectionposition. Light is projected from the lamp 24 by a system of condensinglenses 34, 35. The lenses 34, 35 and the lamp 24 are mounted in a cellwhich is contained in thehousing 22 and is adapted for sliding andpivotal movement relative thereto.

As noted in FIG. 2, the axis of the projection system comprising thelamp 24, the lenses 34, 35 and the tube 72 is slightly offset withrespect to the center line of the base 16 in order to accomodate a traycarrying a plurality of slides. Immediately adjacent to the projectionsystem and having its axis parallel with the axis of the projectionsystem mounted on the deck 60 of the base 10. As shown in FIG. 2, thetray holder is formed as an integral threesided longitudinally extendingbox having a top 74 and two sides '76, '78. Actually, the holder 16comprises two identical box-like structures in axial alignment andprovided with an open area or slot between adjacent ends for permittingegress and ingress of slide transparencies. This is seen in FIG. 2,where a slot 80 is located intermediate the ends of the holder 16. Forpurposes of this invention and further description thereof, the holderis considred to be a unitary structure formed with a slot intermediateits ends.

is the slide tray holder 16 which is suitably The slide tray holder isdesigned to slidably support a slide tray 82 which may be inserted atone end of the holder (left as viewed in FIG. 2) and drawn out at theother end.

The slide pickup and return mechanism comprising a slide transfer devicewill now be described in detail. Mounted adjacent to the opposing sidesof the base 10 and in a transverse plane with respect to the axis of thetray holder 16 is a pair of uprights 99, 92 which serve to support themechanism above the base 10. the uprights 99, 92 is provided with anopening, respectively, for receiving one end of a slide rod 94. AU-shaped slide transfer element 96 is slidably mounted on the rod 94 andis provided with downwardly depending leg portion 169, integrally formedat the ends of the bight por: tion 162 of the element. Suitable openingsformed in the leg portion 100 are adapted to receive the rod 94 forpermitting sliding movement thereon. It will be apparent that thetransfer element 96 is movable between two positions on the rod 94, thatis, between a projection position and a pickup or return position shownin FIG. 2.

Reciprocable movement of the transfer element 96 on the rod 94 iseffected by means of a drive mechanism which includes a rotatable crank103 having an arm 104. The crank 193 is also provided with a second arm107 positioned at 180 from the arm 104 and is made integral on a sleeve.This sleeve is mounted on a shaft 1119 held in a vertical position by apair of vertically spaced bearing supports 112, 114 secured to anupwardly extending support 116 secured to the base 10. As shown in FIG.2, each of the supports 112, 114 is provided with a bearing 11%, 120,respectively, in which the shaft is slidably received. The lower end ofthe shaft has secured thereto a washer 122 which slidably rests upon thebearing for preventing the shaft from falling downwardly in its support.Also secured to the shaft 119 is a clutch sleeve 124 located between thebearings 118, 120, and immediately above this sleeve is a gear 126 whichslidably receives the shaft 116. A circular surface 128 on the sleeve124 is adapted to engage the adjacent face of the gear 126 for impartingrotation to the former during positive driving of the latter. A lightcoil spring 131, held in compression between the upper bearing 118 andthe gear 126, serves to maintain the frictional engagement between thesleeve clutch surface 128 and the gear 126.

Rotation of the shaft 119 and consequently the crank arm 194 is effectedby an electric motor 130 having a drive shaft 132 and a worm gear 134connected thereto and in operative engagement with the gear 126. Uponrotation of the shaft 132, the gear 126 will be correspondingly rotatedand because of the spring induced frictional engagement between the gear126 and the clutch sleeve 124, the rotation will be imparted to theshaft 116. During operation of the projector, there are occasions whenthe rotation of the shaft 110 is abruptly stopped and before the motorshaft 132 is able to come to a complete stop for reasons of the inertialeffects on the armature of the motor 139. In these events, the rotationof the gear 126 would have stopped along with the rotation of the shaft111), however, rotation of the sleeve 124 may continue for a shortduration While the motor 131) is coming to rest. In effect then, theslippage connection between the gear 126 and the sleeve 124 allows themotor to come to a gradual stop rather than an abrupt stop, therebyeliminating damage thereto.

As shown in FIG. 2, a pair of vertically spaced cams 136, 13?) are madeintegral with the sleeve 103 and each of these cams is cooperable with aleaf spring lever 141), 142. The lever 140, when flexed by the earn 136,opens a normally closed load limit switch 144 while Patented July 20,1965 Each of the lever 142, when flexed by the cam 13%, opens a normallyclosed projection limit switch 14-6.

Abrupt braking of the rotation of the crank 103 when the transferelement 96 is in either the projection or pickup positions isaccomplished by means of 'an armature in the form of a plate 148pivotally mounted at one end to the top 74 of the tray holder 16. 151?of the plate 148 extends over the motor 130 and is adapted for limitedarcuate movement in a vertical plane between a stop member 152 securedto the frame of the motor and extending over the end 150 and the motoritself. A leaf spring 154 secured at one end to the top of the armature148 and engageable with the top of the stop 152 prevents sudden slammingof the armature against the motor-while at the same time continuouslybiasing the end 150 in an upward direction against the stop 152. A pin156 is secured to the upper surface of the, armature 148 and iscooperable with the ends of each of the arms 194 and 107 for brakingrotation of the crank 193. When the motor 134) is energized for rotatingthe gear 126, the magnetic flux surrounding the motor is sufficient toattract the armature 148 for rotating the same downwardly against thebias ,of the spring 154. This movement of the armature will besutficient to clear the engagement of the pin 156 with respect to eitherof the arms 104, 107 and thereby permit rotation of the gear 126. Whenthe motor 130 is deenergized, the armature will be forced upwardly forcarrying the pin 156 in the path of either of the, arms 1G4,1tl7'whereupon the rotation of the crank 193 and consequently the gear126 will be positively and abruptly stopped. The mechanical relationshipbetween the transfer element 96, the link 106, the crank 103 and the pin156 is such that this positive stoppage occurs when the transfer elementis in either of its extreme positions on the rod 94.

It will be apparent from the foregoing description that rotation of the,crank'ltlS will cause reciprocation of the transfer element 96 between aslide pickup or return position to a projection position opposite theslide receptacle 30 of the projection-system. The depending leg 100 hassecured at its lower end, a pad 160-for engaging a slide when thetransfer element is moving to the projection system.

As previously stated, the rotation of the shaft 110 will impart rotationto the clutch sleeve 124. Radially projecting from the sleeve 124 is anactuator pin 192 secured within a bore 194 and being adapted forrotation about the axis of the shaft 110 :during rotation of the latter.

The pin 192 is adapted to be received within any one of a plurality ofgrooves 196 of a helical index gear 198 secured to a shaft 200 rotatablymounted horizontally on the panel 29. A gear 202 secured to one end ofthe shaft 269 is cooperable with the rack on the tray 82. The-pitch ofthe grooves 196 on the helical gear 198 is such that rotation of thelatter an angular distance equal to the pitch willadvance the tray 82 adistance equal to the distance between two adjacent slides S. For everyfull rotation of the clutch sleeve 124, the pin 192 will be receivedwithin and slide along one of the grooves 196 for rotating the gear 198and advance the tray.

A cooling system for the lamp 24 and a heating system for preheating theslides before they are projected are provided in the present projector,As shown in FIG. 2, the base It has mounted on the deck thereof anelectric The other end i air is drawn into the base 10 and forcedtherethrough as shown by the arrows. a

A generally circular bafl'le 280 is mounted within the base 10 forcontrolling the flow of air to the open floor of the lamp housing 22.Air is thus forced upwardly through the housing and is expelled throughopen louvers formed in the rear wall of thehousing. In so moving, theair will cool the lamp 24, the heat-absorbing plate 48 and the lenses34,35.

I claim:

1..-A drive mechanism for driving a relatively low inertia load havingmeans for abruptly stopping the load comprising an electric motorgenerating a stray magnetic field, means energizing said motor and adrive train connecting the load and said motor, said drive trainincluding a slip clutch connection between said motor and the load, aninterference stop mounted for movement alternately into and out ofinterference with the drive train on'the load sideof said clutch,yieldable means for urging said stop into interference, a magneticmember mounted adjacent to said motor and connected 'to said stop, saidpermitting said motor to overrun and dissipate its inertial energy aftersaid stop brings the load to an abrupt halt. 2. VA slide transfermechanism for an automatic slide projector or the like comprising arelatively light reciprocatable transfer arm for moving slides betweentwo spaced positions in the projector, a rotatable member connected tosaid arm for reciprocating'it, an electric motorgenerating a straymagnetic field and rotating said member, means energizing said motor, adrive train including a slip clutch connecting said motor and saidmember, an abutment stop movable .into and out of the path of saidmember, means normally urging saidstop into the path of said member, amagnetic actuator adjacent to said motor and connected to said stop,said magnetic member operating in response to the stray magnetic fieldfor moving said stop out of the path of said member in response to andReferences Cited by theiExaminer UNITED STATES PATENTS 2,479,975 8/49Shively 192-142 2,629,475 2/53 Hooker 192-142 2,646,519 7/53 Kalikow etal.

DAVID J. WILLIAMOWSKY, Primary Examiner. THOMAS I. HICKEY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,195,252 July 20, 1965 James A. Clark It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 1, line 34, for -4" read 2-2 same column 1, lines 53, 61 and 67,column 2, lines 3 and 21, and column 3, line 63, for "FIG. 2", eachoccurrence, read FIG. 1 column 1, line 70, for "considred" readconsidered column 2, line 16, after "element" insert 96 Signed andsealed this 22nd day of February 1966.

( L) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

2. A SLIDE TRANSFER MECHANISM FOR AN AUTOMATIC SLIDE PROJECTOR OR THELIKE COMPRISING A RELATIVELY LIGHT RECIPROCATABLE TRANSFER ARM FORMOVING SLIDES BETWEEN TWO SPACED POSITIONS IN THE PROJECTOR, A ROTATABLEMEMBER CONNECTED TO SAID ARM FOR RECIPROCATING IT, AN ELECTRIC MOTORGENERATING A STRAY MAGNETIC FIELD AND ROTATING SAID MEMBER, MEANSENERGIZING SAID MOTOR, A DRIVE TRAIN INCLUDING A SLIP CLUTCH CONNECTINGSAID MOTOR AND SAID MEMBER, AN ABUTMENT STOP MOVABLE INTO AND OUT OF THEPATH OF SAID MEMBER, MEANS NORMALLY URGING SAID STOP INTO THE PATH OFSAID MEMBER, A MAGNETIC ACTUATOR ADJACENT TO SAID MOTOR AND CONNECTED TOSAID STOP, SAID MAGNETIC MEMBER OPERATING IN RESPONSE TO THE STRAYMAGNETIC FIELD FOR MOVING SAID STOP OUT OF THE PATH OF SAID MEMBER INRESPONSE TO AND HOLDING SAID STOP OUT OF THE PATH DURING ENERGIZATION OFSAID MOTOR, MEANS BREAKING THE CONNECTION BETWEEN SAID MOTOR AND SAIDENERGIZING MEANS, AND SAID SLIP CLUTCH DRIVE CONNECTION PERMITTING SAIDMOTOR TO OVERRUN AND DISSIPATE ITS INERTIAL ENERGY AFTER SAID STOPBRINGS SAID MEMBER TO AN ABRUPT HALT UPON DEENERGIZATION OF SAID MOTOR.